(I) Field of the Invention
The present invention relates to the general field of catalysts and processes applicable to the conversion of hydrocarbons particularly the conversion of heavy oils contaminated with substantial amounts of metals and carbon e.g. reduced crudes.
In the evolution of catalytic cracking, the process has gradually evolved from a hardware standpoint, until it has reached its present state of development in fluid catalytic cracking of vacuum gas oils. However, some of the considerable advances in hardware have come about as a result of the introduction of new and very unique catalysts (namely the introduction of the zeolite catalyst which enabled the hardware to evolve to riser cracking with very short contact times).
Likewise, in reduced crude conversion of carbometallic oils, a process has been developed (Myers, Busch U.S. Pat. No. 4,299,687) with all its attendant hardware, designed to facilitate the conversion of these high boiling residues into high octane gasoline with low capital investment and operating costs. However, it was fully appreciated that in order to realize the tremendous potential volume conversion to liquid transportation products existant in reduced crude, that highly selective catalysts would be required.
As pointed out in our letter to the editor of Science (reference 1980) it has been the intent of research to evolve a catalyst which could, in this process, utilize all the hydrogen and carbon in a most efficient manner. It was pointed out in that article that there is sufficient hydrogen available so as to convert all of reduced crude into a combination of toluene and pentenes in greater than 100 volume % yield, and with high octanes over 100, and that the only limiting factor to achieving such a result was the catalyst.
With that realization in mind, the inventors of this new catalyst have sought by very intensive research means to create a catalyst which, when harnessed with the unique features of the reduced crude conversion process, serve to obtain a yield of liquid transportation products previously not considered possible. In order to achieve this objective, it has been necessary that all aspects of catalytic conversion be considered and that all those properties required to reduce coke and hydrogen production, increase gasoline and light cycle oil yield, immobilize or reduce the effect of vanadia, inhibit the adverse effects of nickel, facilitate cracking in the presence of high molecular weight molecules so as to achieve cracking in the sieve, and also to operate in the presence of high molecular weight basic nitrogen compounds which tend to neutralize acid sites be optimized. In our invention, all of these features were concentrated on, and optimized, so as to produce a metal resistant, high performance catalyst to be harnessed with this new reduced crude conversion process.
(II) Description of the Prior Art
Because of the economic importance of the field of the present invention, a number of patent applications and technical publications have been addressed to the search for catalysts which will provide the most valuable product distribution while maintaining their activity and which are produceable at reasonable cost. The Assignee of the present application has itself directed substantial activity to the field of heavy oil conversion and its patents and pending applications include:
U.S. Pat. No. 4,347,624 to George D. Myers filed Nov. 14, 1979 PA1 U.S. Pat. No. 4,347,122 to George D. Myers et al filed Nov. 14, 1979 PA1 U.S. Pat. No. 4,299,687 to George D. Myers et al filed Nov. 14, 1979 PA1 U.S. Pat. No. 4,354,923 to George D. Myers et al filed Nov. 14, 1979 PA1 U.S. Pat. No. 4,332,673 to George D. Myers filed Nov. 14, 1979 PA1 U.S. Ser. No. 296,679 to W. P. Hettinger, Jr. et al filed Aug. 27, 1981 PA1 U.S. Ser. No. 263,391 to W. P. Hettinger, Jr. et al filed May 13, 1981 PA1 o reduce and minimize coke and hydrogen production, PA1 o maximize gasoline and light cycle oil yield, PA1 o immobilize or reduce the effect of vanadia, PA1 o inhibit or reduce the adverse effect of nickel, PA1 o facilitate cracking in the presence of high molecular weight molecules so as to achieve cracking in the sieve, PA1 o operate in the presence of high molecular weight basic nitrogen compounds which tend to neutralize acid sites, PA1 o operate in the presence of large coking molecules such as asphaltenes, without allowing these macro molecules to block access of smaller molecules to catalyst sites. PA1 o be economically acceptable. PA1 A. Low catalytic coke production; PA1 B. High light catalytic cycle oil (LCO) to slurry oil (Slurry) ratio in products; PA1 C. Excellent resistance to metal contamination and poisoning; PA1 D. Excellent cracking activity in the presence of high metals containing feedstocks; PA1 E. Stability under high temperatures permitting severe regeneration conditions to remove the high amounts of carbon laid down by residual oils; PA1 F. high gasoline selectivity and production; PA1 G. low slurry production; PA1 H. high octane gasoline; PA1 I. Good resistance in terms of catalytic cracking of high basic nitrogen containing feedstocks; PA1 J. High activity while exposed to large asphaltene molecules. PA1 K. Is acceptably low in cost.
Filtrol Corporation patents and literature include:
______________________________________ U.S. Pat. No. 4,058,484 Alafandi NH.sub.4 - faujasite U.S. Pat. No. 4,085,069 Alafandi NH.sub.4 - faujasite in a matrix U.S. Pat. No. 4,086,187 Lim attrition resistant catalyst U.S. Pat. No. 4,100,108 Alafandi 2 zeolites in matrix U.S. Pat. No. 4,192,778 Alafandi RE exchanged faujasite U.S. Pat. No. 4,198,319 Alafandi faujasite + Si--Al gel (50-70% SiO.sub.2) + clay U.S. Pat. No. 4,206,085 Lim faujasite + Al.sub.2 O.sub.3 + silica sol U.S. Pat. No. 4,215,016 Alafandi NaY + cations exchange at &lt;500.degree. F. under pressure U.S. Pat. No. 4,234,457 Alafandi RE exchange of Si--AL matrix U.S. Pat. No. 4,252,684 Alafandi RE exchange of Si--AL matrix U.S. Pat. No. 4,224,188 Alafandi exchange of NaY with Al ion, then NH.sub.4 ion U.S. Pat. No. 4,228,137 Taylor produce faujasite by seeding with clay from halloysite U.S. Pat. No. 4,237,031 Alafandi RE exchange of ammonium Si--Al matrix under temp-pressure U.S. Pat. No. 4,246,138 Alafandi RE exchange of ammonium Si--Al matrix under temp-pressure U.S. Pat. No. 4,259,210 Alafandi RE exchange of ammonium Si--Al matrix under temp-pressure U.S. Pat. No. 4,142,995 Alafandi RE faujasite in Si--Al matrix U.S. Pat. No. 4,253,989 Lim REY + Clay + Al.sub.2 O.sub.3 + 0.5-3.5% SiO.sub.2 U.S. Pat. No. 4,269,815 Lim NaY - multiple exchange with NH.sub.4 under temp-pressure U.S. Pat. No. 4,310,441 Alafandi large pore Si--Al from cationic to anionic Al sources with 0.6 cc/g PV in 20-600 A range U.S. Pat. No. 4,325,845 Lim zeolite in matrix (clay + silica gel from Na silicate) U.S. Pat. No. 4,325,847 Lim zeolite in matrix (pseudoboehmite + alumina gel) U.S. Pat. No. 4,333,857 Lim zeolite &lt;3 microns in matrix of pseudoboehmite, clay, silica sol ______________________________________ Article "New Generation of FCC Catalyst", E. J. Demmel and J. C. Lim, API Proceedings, Vol. 58, Pg. 29-32, April 1975, Reprint 04-79.
Mobil Oil Company's patents include:
______________________________________ Mobil Oil Company's patents include: ______________________________________ U.S. Pat. No. 3,790,471 Argaver ZSM-5 U.S. Pat. No. 4,088,605 Rollman ZSM-5 with an Al.sub.2 O.sub.3 free outer shell U.S. Pat. No. 4,148,713 Rollman ZSM-5 with an Al.sub.2 O.sub.3 outer shell U.S. Pat. No. 4,203,869 Rollman ZSM-5 with an Al.sub.2 O.sub.3 free outer shell U.S. Pat. No. 4,199,556 Plank ZSM-5 formed with N-cpds U.S. Pat. No. 4,205,053 Rollman ZSM-5 formed with N-template and N basic cpd. U.S. Pat. No. 4,139,600 Rollman ZSM-5 formed by use of diamines U.S. Pat. No. 4,151,189 Rubin ZSM-5 formed by use of 2-9 carbon containing primary monoalkylamine U.S. Pat. No. 4,285,922 Audel ZSM-5 formed by use of alkyl ammonium- N-oxide U.S. Pat. No. 4,100,262 Pelrine Cobalt containing ZSM-5 U.S. Pat. No. 4,273,753 Chang HZSM-5 type, produced through use of halide or oxyhalide to dealuminate zeolite U.S. Pat. No. 4,275,047 Whitton ZSM-5 produced by seeding with Nu-1 crystal ______________________________________
Davison Chemical Division of W. R. Grace's patents include:
______________________________________ U.S. Pat. No. 3,595,611 McDaniel PCY zeolite + Al.sub.2 O.sub.3 thermal stabilization U.S. Pat. No. 3,607,043 McDaniel PCY zeolite + Al.sub.2 O.sub.3 thermal stabilization U.S. Pat. No. 3,692,665 McDaniel PCY zeolite + Al.sub.2 O.sub.3 thermal stabilization U.S. Pat. No. 3,676,368 Scherzer REHY zeolite + SiAl hydrogel + mordenite or type A U.S. Pat. No. 3,894,940 Scherzer REHY zeolite + SiAl hydrogel + mordenite or type A U.S. Pat. No. 3,925,195 Scherzer REHY zeolite + SiAl hydrogel + mordenite or type A U.S. Pat. No. 3,293,192 Maher Z14-US U.S. Pat. No. 3,449,070 McDaniel Z14-US U.S. Pat. No. 3,867,310 Elliott CREY U.S. Pat. No. 3,957,623 McDaniel CREY U.S. Pat. No. 3,650,988 Magee Similar to Super D U.S. Pat. No. 3,986,946 Baker Zeolite - SiO.sub.2 --MgO-- F U.S. Pat. No. 4,107,088 Elliott addition of Ti or Zr to matrix U.S. Pat. No. 4,126,579 Flaherty silica gel - zeolite slurry (new spray nozzle design) U.S. Pat. No. 4,218,307 McDaniel USY (NaY + RE .fwdarw. heat .fwdarw. acid treat) Si/Al U.S. Pat. No. 4,144,194 Guidry faujasite + silicate from zeolite preparation U.S. Pat. No. 4,164,551 Elliott Y zeolite preparation - silicate solution for matrix U.S. Pat. No. 4,166,099 McDaniel Y zeolite preparation - seeded with zeolite &lt;0.1 microns U.S. Pat. No. 4,175,059 Edwards K faujasite platelet type shape U.S. Pat. No. 4,178,352 Vaughn Y zeolite preparation U.S. Pat. No. 4,247,420 Doumoulin Si--Al cogel + zeolite U.S. Pat. No. 4,332,699 Nozemack Al.sub.2 O.sub.3 precipitated onto a zeolite U.S. Pat. No. 4,333,859 Vaughn CSZ-3 Co-containing zeolite U.S. Pat. No. 4,340,573 Vaughn Y zeolite preparation - zeolite from prep as seeds U.S. Pat. No. 3,402,996 Maher NaY + RE .fwdarw. Calcination - multi-step exchange and calcination yielding Z14-HS & Z14-US ______________________________________
Patents of others include:
______________________________________ U.S. Pat. No. 4,215,015 Tu (UOP) zeolite in a Si--Al matrix plus polymer; the polymer is burned out leaving a pore structure in the 100-300 A range; Ti can be added to matrix. U.S. Pat. No. 4,239,615 Tu (UOP) zeolite in a Si--Al matrix plus polymer; the polymer is burned out leaving a pore structure in the 100-300 A range; Ti can be added to matrix. U.S. Pat. No. 4,299,733 Tu (UOP) zeolite in a Si--Al matrix plus polymer; the polymer is burned out leaving a pore structure in the 100-300 A range; Ti can be added to matrix. U.S. Pat. No. 4,333,821 Tu (UOP) zeolite in a Si--Al matrix plus polymer; the polymer is burned out leaving a pore structure in the 100-300 A range; Ti can be added to matrix. U.S. Pat. No. 4,263,174 Tu (UOP) spray dried catalyst + RE salt solution; then dried but not washed; this gives RE by exchange and impregnation U.S. Pat. No. 4,269,813 Klotz Borosilicate (Amoco) zeolite U.S. Pat. No. 4,285,919 Klotz Borosilicate (Amoco) zeolite U.S. Pat. No. 4,327,236 Klotz Borosilicate (Amoco) zeolite U.S. Pat. No. 4,036,739 Ward (Union) NH.sub.4 exchange - steam treat - NH.sub.4 exchange (&lt;1% Na.sub.2 O) in zeolite U.S. Pat. No. 4,239,654 Gladrow USY + ZSM in a (Exxon) matrix U.S. Pat. No. 4,308,129 Gladrow USY (5-40%) + (Exxon) 5-40% Al.sub.2 O).sub.3 + 40-90% Al.sub.2 O.sub.3 U.S. Pat. No. 4,147,613 Gladrow 3-16% zeolite in (Exxon) matrix of SiO.sub.2 -- Al.sub.2 O.sub.3 --ZrO.sub.2 + 15-40% Al.sub.2 O.sub.3. This produces a catalyst having at least 0.4 cc/g of its pore volume in pores &gt;90.degree. A. U.S. Pat. No. 4,151,119 Gladrow 3-16% zeolite in (Exxon) matrix of SiO.sub.2 -- Al.sub.2 O.sub.3 --ZrO.sub.2 + 15-40% Al.sub.2 O.sub.3. This produces a catalyst having at least 0.4 cc/g of its pore volume in pores &gt;90.degree. A. U.S. Pat. No. 4,283,309 Gladrow 3-16% zeolite in (Exxon) matrix of SiO.sub.2 -- Al.sub.2 O.sub.3 --ZrO.sub.2 + 15-40% Al.sub.2 O.sub.3. This produces a catalyst having at least 0.4 cc/g of its pore volume in pores &gt;90.degree. A. U.S. Pat. No. 4,292,169 Gladrow 3-16% zeolite in (Exxon) matrix of SiO.sub.2 -- Al.sub.2 O.sub.3 --ZrO.sub.2 + 15-40% Al.sub.2 O.sub.3. This produces a catalyst having at least 0.4 cc/g of its pore volume in pores &gt;90.degree. A. U.S. Pat. No. 3,442,795 Kerr (Mobil) Stabilization of NH.sub.4 to yield a high Si/Al ratio zeolite U.S. Pat. No. 3,493,519 Kerr (Mobil) Stabilization with NH.sub.4 to yield a high Si/Al ratio zeolite U.S. Pat. No. 3,553,104 Stover A matrix of a pore (Mobil) volume &gt;= 0.6 cc/g U.S. Pat. No. 4,219,406 Kuehl Si--Al hydrogel + (Mobil) zeolite is spray dried, exchanged with NH.sub.4 --Al--RE ions then washed, dried and impregnated with RE's U.S. Pat. No. 4,219,446 Kuehl Si--Al hydrogel + (Mobil) zeolite is spray dried exchanged with NH.sub.4 --Al--RE ions then washed, dried and impregnated with RE's U.S. Pat. No. 4,326,993 Chester 1-75% zeolite + (Mobil) colloidal SiO.sub.2 + colloidal Al.sub.2 O.sub.3 + clay and 40% of pore vol. in 30-300A sized pores USSN 195848 100ct1980 (French Demande Gladrow 2,491,777; 97CA 58340e) ultra stable Y-type zeolite 20%, porous Al.sub.2 O.sub.3 particles 20%, silica-alumina gel matrix 60% and uniformally distributed rare earth oxides 0.01-0.08% used to crack gas oil (not heavy oil) to gasoline with conversion of 73.2% ______________________________________
Processing of the higher boiling fractions of crude oil in a fluid catalytic cracking unit has been practiced for many decades. The expertise developed has been along the lines of an easily vaporizable feed such as vacuum gas oil (VGO) containing very little contaminants. Thus, for many years, those skilled in the art have been concerned with developing catalysts having improved activity, improved selectivity, improved stability, and metal tolerance related to mild operations. By mild operations we refer to (1) feed contaminants being low (Conradson Carbon below 2 WT%, Ni+V contents of the feed below 5 ppm, endpoint of feedstock at 566.degree. C. (1050.degree. F.) (thus 100% vaporizable under process conditions), (2) mild process conditions (regenerator temperatures below 704.degree. C. (1300.degree. F.), no need to employ excessive amounts of steam and water as lift gas and coolants to maintain unit heat balance); this is also due to low coke make, (3) catalyst properties with low porosity to reduce carryover of gases and hydrocarbon to regenerator, (4) catalyst stability--metal tolerance of matrix and zeolite not critical due to low metal deposition, and low regenerator temperature. The bad metal actor is nickel which is controlled by antimony addition.
The following table illustrates the changes in process severity and catalyst needs with feedstock change:
TABLE I __________________________________________________________________________ VGO VGO + RESID REDUCED CRUDE __________________________________________________________________________ FEEDSTOCK PROPERTIES VGO % 100 95 -- Heavy Resid % -- 5 -- Reduced Crude % -- -- 100 Feed Endpoint .degree.F. 1050 1300 up to 1800 Conradson Carbon 0.2 1-2 4-12 Metals ppm 0.2 5 10-200 PROCESS CONDITIONS Reactor Temp..degree.F. 940 940-960 945-1050 Regenerator Temp .degree.F. 1150-1200 1200-1300 1300-1400 Steam H.sub.2 O addition &lt;1% 1-2% 5-20% wt. % feed CATALYST PROPERTIES Metals on Catalyst ppm 500-1000 1000-3000 3000-20,000 Carbon on Catalyst - 4-5 6-8 8-16 wt. % feed Effect of Ni H.sub.2 -coke H.sub.2 -coke H.sub.2 -coke Effect of V nil nil H.sub.2 -coke and zeolite- matrix destruction Pore size-Angstroms varied varied 100-1000.ANG. + larger Pore Volume cc/gm 0.2-0.3 0.3 0.4-0.5 or more Acidity in the Matrix No No Yes Metal Passivation Ni Ni w/Sb Ni w/Sb Ni w/Sb, + La + Ti + Al.sub.2 O.sub.3 Metal Passivation V V-nil V-nil V w/La + Ti + Al.sub.2 O.sub.3 Effect of Basic Nitrogen nil nil Great __________________________________________________________________________
To one skilled in the art the extension of known catalyst properties when processing of VGO to processing VGO+ small amounts of resid requires only a small adjustment or fine tuning of VGO catalysts properties to take care of the changes in process and feedstocks, e.g., small increases in metal content, Conradson Carbon, regenerator temperatures, and feedstocks. This is demonstrated by the above patent literature in which individual properties have been varied to change or accent a single catalyst property or process variable.
However, in none of the attached references is the total concept of catalyst development for reduced crude processing anticipated by adopting zeolite type, cracking activity balanced by acid site strength (Bronsted and Lewis acids); partial rare earth addition; rare earth type; matrix properties such as activity, acidity, and proper matrix porosity; metal control through acidic site exchange; passivation and immobilization of nickel and vanadium; sieve accessibility; absorption and vaporization of heavy hydrocarbons; resistance to nitrogen poisoning and high sulfur levels; able to function at high process temperatures through selective cracking; thermal-hydrothermal stability of matrix and zeolites; low coke formation through choice of zeolite system and concentration in matrix; and still maintain a cost effective catalyst allowing reasonable addition rates. Thus, the processing of reduced crude in a fluidized process employing the catalyst of this invention is a significant advance in catalyst development because it requires the utilization and the balance in a most highly developed form of the aforementioned properties.
The catalyst of this invention is also such an advance in which a select zeolite, having excellent thermal-hydrothermal stability through selected properties of silica-alumina ratio (unit cell constant), is only partially rare earth exchanged so as to enjoy a balance of acidity or activity via Bronsted and Lewis acid sites. This balance is critical to product distribution and to maintaining the optimum amount of acid sites or cracking sites in the unit to avoid overcracking and increased coke production. The amount of acidity present in the matrix is also balanced with zeolite acidity so as to maintain high selectivity to gasoline and avoid overcracking and coke deposition. Thus, there is a balance between zeolite properties and zeolite concentration in the matrix and the properties of the matrix itself to attain the aforementioned selectivities (gasoline-coke). In addition, the rare earth utilized is lanthanum rich so that a higher hydrothermal stable zeolite, also more resistant to vanadia, is obtained with better metal tolerance.
The matrix of the catalyst of this invention is as vital a part of the total catalyst as is the zeolite. The matrix must have the following properties: proper and selective pore size distribution, large pore volume, metal tolerance and metal immobilization properties, in addition to the typical properties of particle size distribution, density and good attrition index. Most importantly, it is necessary that the matrix also possess a considerable amount of, and stable acidity, in order to achieve molecular size reduction which permits a molecule entrance into the highly active zeolite. A critical balance between sieve and matrix acidity and acid strength as well as matrix resistance to thermal, hydro-thermal and metals deactivation must also be achieved so that sieve and matrix acidity remain coupled and balanced as the catalyst ages.
The porosity (pore size-volume) of a catalyst is critical when processing reduced crudes. Since the catalyst of this invention requires an acidic matrix to crack the higher boiling components above 540.degree. C. (1000.degree. F.) to lower boiling fragments to ensure total vaporization of the feed, and to permit access of larger molecules to sieve pores, a specific pore volume and pore size distribution is required to ensure that all liquids and vapors can be absorbed and transported to the zeolite and all products transported away from the zeolite without encountering diffusional problems. Furthermore, a large pore volume is required to accommodate liquids depositing in the pores, and coke and metals depositing in the pores without affecting transport (diffusional problems) of feed liquid and vapors to and product vapors from the zeolite particle.
Finally, an additional property is incorporated into the matrix in the form of metal passivators, immobilizers, and/or sacrificial sieves or traps. This involves the incorporation of such as alumina, titania or zirconia to immobilize nickel and vanadia, the precipitation of lanthanum into the matrix to immobilize vanadia, or the addition of less expensive sieves to serve as sacrificial sieves in order to spare the performance of the catalytic zeolite. It should be noted that the impregnation or exchange of La into the matrix is much less effective for Ni-V immobilization. It is preferred that the La be precipitated onto the matrix.
It will be noted that the multi-concepts and combinations incorporated into the development of the catalyst of this invention for reduced crude processing is not readily available from the literature and required development of the concepts singularly and then on a multi-compositional basis.
Despite all of the work evidenced by the above patents, and by many others in this general field, the prior investigators have not combined the selected reactivity and physical properties of zeolites, silica-alumina gels, clays, aluminas, rare earths, and other additives to achieve the low coke, low H.sub.2, high octane, high activity, high gasoline selectivity, low slurry oil, metals tolerant and high thermal and hydrothermal stability of the catalysts described in this application. Prior commercial catalysts produce undesirable levels of slurry oil or produce too much catalytic coke.
Stability of prior catalysts, especially when loaded with metals such as vanadia at higher regenerator temperatures has also been a serious problem. The lack of metal poisoning resistance of prior catalysts has, over the past 40 years, been perhaps the single most difficult problem and barrier to the production of transportation fuels from residual oils.